Belt squeal. Why?

[op1133882]

I have a 1983 k10 Scottsdale. It has a 350 originally had a 305 not sure when the swap happened. It has a remanufactured power steering pump that was put in a few months ago. It has a remanufactured alternator that was put in a few months ago. Recently I've had belt squeal issues. Can't figure out why. I've spent plenty of time lining up the pulleys perfectly. Tried two different alternator brackets. Belts have proper tension. I am almost certain it it the alternator pulley. Squealing happens every time I start the truck. Lasts from about a minute up to three minutes. Usually when it stops it doesn't come back until the truck is turned off and back on again. Right after it stops and I turn the lights on it will sometimes come back again. This leads me to believe that it has something to do with a load on the battery. Can a failing battery cause these symptoms? I've put enough money into this issue trying to figure it out. Anybody have any ideas/suggestions? Any help is greatly appreciated
Thanks


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[bd]

Welcome to the Forum!

You probably have a loose belt.  Some bargain belts don't hold their shape or diameter well and some don't provide adequate friction, so will slip.  Brand name belts manufactured by GM, Goodyear, Gates, Dayco, etc are more consistent in their quality and provide good performance.  That said, with the engine cold and shut off, grab the alternator fan with your fingers while wearing gloves or using a shop rag and try as hard as you can to turn the pulley.  If the belt doesn't hold the pulley secure and the pulley spins, the belt isn't tight enough (or the belt material is inferior and doesn't create sufficient friction).  Adjust the belt and try again.

Power steering belt adjustment is always a challenge on these trucks.  If you use a pry bar against the pump reservoir it can crush the can and cause leaks.  To achieve adequate belt tension on the P/S pump, Thexton makes an effective tool that hooks the P/S bracket allowing you to tighten the belts without damage to the reservoir.

[op1133882]

Thanks, I will check it out tomorrow. I am pretty sure belts are tight enough. That is the first thing I made sure of before anything else. I'll double check it tomorrow


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[FlatBlack77]

can you post a few pics of the pulley/belt setup? it might be of use.

thats a fancy little tool BD. i had no idea they made something like that. i use a long rod or a pry bar turned sideways put down between the pump and the pulley and use the heads of the bracket-to-pump bolts to pry against

[K20Detroit]

You can try a few things;
Check the pulley for glaze. If it feels very smooth, rough it up a little with sand paper, a wire brush, etc.
Check the battery voltage before you start the truck, and while the squeeling is happening. See if it is squeeling from alternator stress.
Are the pulleys the proper sizes? Not undersize for more power or anything? This is a cause of squeeling, for sure.

[bd]

thats a fancy little tool BD. i had no idea they made something like that. i use a long rod or a pry bar turned sideways put down between the pump and the pulley and use the heads of the bracket-to-pump bolts to pry against

I used to do the same thing with a HUGE screwdriver among other things.  Another method was to place a short 1 X 2 block of wood between a pry bar and the reservoir to distribute the force over a larger surface.  Once I tried the Thexton tool, it worked so well with so little effort that all other methods became passe.  You can tension the belt as tight as you want it and not worry about any damage or bad consequences.

I am pretty sure belts are tight enough. That is the first thing I made sure of before anything else. I'll double check it tomorrow.

The method I described for checking the alternator belt adjustment applies to any belt driven alternator in any truck or automotive application.  If insufficient friction exists between the belt and the pulley, this method will expose it.

[op1133882]

There's the setup. Power steering belt is a little older but it's nice and tight with good friction. 
Alternator belt is new and tight but it definitely has poor friction, I can turn the pulley by hand and it slips. I'm going to buy a better quality belt and while it's off I'll rough up the pulley surface a bit. Fingers crossed. Thanks guys


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[bd]

Looking at the image, the existing alternator belt is too narrow for the pulley grooves!  Purchase a wider belt that rides flush or just proud of the water pump pulley and you will increase the contact surface (friction) between the belt and the alternator pulley.  Then adjust the belt as previously recommended.

[zieg85]

belt looks fine on the other pulleys as far as I can tell, alternator pulley looks wrong, too big for the 7 series Gates belts is my observation...

[bd]

Ignoring the alternator, the belt sits slightly deep in the water pump pulley.  Look at the belt height in the image of the P/S pump.  The alternator belt should ride about the same height in the water pump pulley.  That little bit can make a difference.

[op1133882]

The belt seems to sit fine in all pulleys except the alternator pulley. I'll try a new pulley and a new belt


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[bd]

Could be the way my monitor is rendering the image.

[FlatBlack77]

the problem is that the water pump pulley has 2 grooves that are the same size. the crank pulley grooves you are using are 2 different sizes. so the crank pulley is turning the 2 belts at 2 different speeds and since they are both going on the water pump pulley with identical grooves, the belts are fighting each other at the water pump pulley. so the belt with the least grip is going to slip

i had this same problem almost exactly. only difference was my crank pulley grooves were the same and the water pump pulley grooves were different. it would come and go because the belt got worn smooth and it would just slip most of the time. rubber dust was everywhere

[bd]

That's a great observation!  Hidden in plain sight.  lol  Well done!

[op1133882]

Awesome. Just ordered a new crankshaft pulley. I'll let you know how it works out. Thanks!


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